Fri Sep 26, 2008 10:37 pm
The most apparent difference between the two films is that Delta 400 exhibits finer grain than HP5. After that the differences are more subtle.
Delta 400, being a "next generation" emulsion, not only is finer-grained, but the grain is arranged in a more orderly way, resulting in a somewhat smoother overall rendering of an image. By comparison, HP5 has a slightly harder, coarser quality. This is not to say that one film is better or worse, just different —and that difference can be more or less subtle depending on exposure and development.
A preference for using one film over the other would come down to personal taste. In my own 35mm experience, I would use HP5 for a more 'old school' grittier look and Delta 400 for best overall quality and detail in a 400 speed black and white film. —Be aware though, that these characteristics are best exploited with good processing and printing.
P.S. I would not recommend developing these two films together. For one thing, Delta 400 requires about 50% more fixing time that HP5 does.
Ken